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By Frances Carroll, Jack Cochran, and Amanda Rigdon
As medical cannabis becomes more frequently prescribed, demand is
growing for analytical testing services to perform potency testing to
determine the levels of therapeutic compounds in cannabis products.
While interest in terpene profiling and pesticide residue analysis is
also increasing, accurate potency testing remains the cornerstone
of every medical cannabis lab, and it is critical that this testing be
carried out in the most efficient way possible. Cannabis potency test-
ing can be performed reliably using either LC or GC methodologies.
However, in cases where separate quantification of the acid forms of
cannabinoids (e.g., delta-9-tetrahydrocannabinolic acid A [THCA] and
cannabidiolic acid [CBDA]) is required, LC is the most viable quantita-
tive option. Rules for quantification of cannabinoids for potency test-
ing vary by state, and the choice of technique is determined by both
these regulations and by existing laboratory constraints. This article
will outline LC and GC approaches to potency testing. Restek has
been committed to helping medical cannabis labs establish sound
analytical practices from the beginning of this emerging industry
through its recent years of rapid growth. Here we provide products
and methodology for accurate, high-throughput potency testing by
LC and GC so that you can improve productivity and get more done
in a day, regardless of current instrumentation.
Analyze Cannabinoids at UHPLC Speed
without Investing in New Equipment
Instrumentation is one of the largest investments made when start-
ing a new medical cannabis testing lab. In setting up potency testing,
higher throughput is attractive in order to get the most out of your
instrument investment. However, the cost of a UHPLC instrument
is significantly more than that of a conventional HPLC instrument.
Now, you can get UHPLC performance out of any HPLC instrument
using Restek’s Raptor™ line of HPLC columns. The superficially porous
particles used in these columns allow for faster flow rates and higher
efficiency than conventional fully porous particles, without the high
backpressure of sub-2 µm particles used with UHPLC instruments.
As shown in Figure 1, Restek has developed a fast analysis (3.8 min
analysis [7 min total cycle time]) of cannabinoids that can be per-
formed on any LC instrument. By utilizing Raptor™ column technolo-
gy, you can obtain UHPLC speed without the capital investment. Also,
we specifically chose simple, fast, and easy-to-prepare mobile phases
that can be directly transferred to LC-MS if you ever need to switch
due to regulation changes. Raptor™ columns enable you to keep your
start-up capital available while at the same time building a flexible and
fast analytical foundation.
Rxi®-35Sil MS GC Column Provides Baseline
Separations for More Accurate Reporting
GC instruments are the workhorses of labs in many industries, and
reliable, used instruments can be purchased at a very reasonable cost.
In cases where separate quantification of cannabinoid acids is not
required, GC is often the technique of choice for cannabis potency
testing. Restek has developed a method for cannabis potency testing
using the Rxi®-35Sil MS column, due to its ruggedness and selectiv-
ity. All columns in the Rxi® family have high thermal stability, making
them very rugged, which results in a longer lifetime and reduced
consumables costs. In addition, the high phenyl content selectivity of
the Rxi®-35Sil MS column provides much better separation of canna-
bichromene (CBC) and cannabidiol (CBD) than what can be achieved
using traditional 5-type columns. Using cost-effective hydrogen car-
rier gas, all cannabinoids are baseline separated in a very fast analysis.
Additionally, by consolidating quantification into only the neutral
forms of cannabinoids, the need for expensive cannabinoid acid stan-
dards is eliminated.
High-Throughput Cannabis Potency Methods
for LC and GC Produce Results Quickly
without the Cost of New Equipment
Whether you are testing potency by LC or
GC, Restek has the products and expertise
to get you accurate results quickly so you
can analyze more samples per day.
Acknowledgement
The Ferguson Township Police Department supplied seized marijuana and oversaw sample
handling. Frank Dorman at The Pennsylvania State University assisted with sample extraction.